This
painful state comes from the sun burning your eye cornea. It occurs if
you don’t wear sunglasses at altitude.When climbing on
oxygen, the warm and moist breathing air will escape your oxygen mask
upwards and sometimes clog up your goggles, especially upon climbing
down.
Your choice will then be to climb "blindfolded" or
remove the glasses. You might choose to pull your glasses a bit out from
your face, allowing the warm air to pass them. The suns rays will now be
able to burn your eyes at the unprotected sides.
If the weather is overcast you might be tempted to
remove the glasses altogether. Yet the rays are just as harmful when
cloudy, and the following morning you’ll be sorry. After 8 years of
climbing it finally happened to us. It took only a short time without
goggles at our summit descent (shooting film), we noticed nothing, and
in the morning we were a mess.
Try to keep the glasses on and bring snow blindness
medical drops in case you get blinded after all. The ointment will
considerably speed up your recovery.